Evaluation of Event-Based Sensors for Satellite Material Characterization

Abstract

Broadband photometry has been used for many years to infer basic information about satellites; however, there has been limited success at remotely determining satellite surface materials, and the variability of brightness and spectral energy distribution of satellite reflections complicates satellite identification. This paper demonstrates the potential utility of event-based sensors for remotely characterizing satellites based on the reflectance properties of their surface materials. Event-based sensors offer three important advantages over traditional frame-based sensors, such as charge-coupled devices (CCDs) for characterizing satellite materials on orbit: very high temporal resolution, high dynamic range, and low data rates. This allows rapid, fine-resolution measurements over a broad range of intensities. An event-based camera was used to characterize the broadband reflectance properties of five common satellite materials over a range of illumination and observation angles in the laboratory. Some of the results are very distinctive, and have not previously been reported, demonstrating that event-based sensors might perform better than CCDs at satellite identification and material characterization. The results also show that different materials can exhibit quite different, and sometimes very distinctive, illumination/observation geometry-dependent reflectance characteristics. Using high angular resolution event-based data to assess broadband reflectance changes with changing geometry could be an effective means of unambiguously identifying satellites or determining the presence of specific satellite surface materials.